Digital video systems generally communicate a sequence of digital images from a source, such as a camera, to a destination, such as a display. The communication can be directly from a camera to a live display or the communication can be time delayed by storing the video and displaying it at a later time. The digital images may be compressed or communicated in their native format.
Various system failures within a digital video system may cause the sequence of images to stop, or to lock-up, resulting in a frame freeze condition. Examples of such failures may be camera lock-up, electronics lock-up, communications fault, storage failure, repeated frames, skipped frames, or partial frames. In some critical applications, it is important for an operator to know quickly that the video system has failed. This may be especially true where a static image on the operator's display may cause the operator to erroneously conclude that scene at the source is simply not changing, when in fact the video system is not operating properly. Some examples of critical applications are security monitoring, medical monitoring, military surveillance, navigation, or manufacturing system tracking.
Attempts to ensure against video system frame freeze have included calculating a checksum, or cyclic redundancy check (CRC) value for each frame at the receiver to determine if it is different than the previous frame. If the calculated value changed from frame to frame, then it could be assumed that the video was not frozen. Calculating such values over the entire two dimensional array of a video frame can be computationally complex and may consume considerable computer time and computer power. Additionally, there may be instances where the image actually did not change, such as a still portion of a video, which may result in the checksum value or CRC value remaining unchanged between frames. Also, two rather different video frames may just happen to have the same checksum value or CRC value which could result in false indications of video system lock-up.
It is with respect to these considerations and others that the disclosure made herein is presented.